Send Your Secret Spy Messages Wirelessly Through Light with This DIY Laser Audio Transmitter
Looking to transmit some super-secret audio communications to your other spy buddies? A laser is the perfect tool for getting your sounds heard from a small distance—without anyone intercepting them— even if it's just a cover of your favorite pop song.
A laser audio transmitter uses light rather than radio waves to transmit sound. This is a much more secure way to send audio communications because the laser is a focused beam of light, whereas radio waves are not controlled, so they can be picked up by anyone.
The transmitter is composed of a laser module, audio output transformer, power source, and photo resistor, plus a pair of headphones and some sort of audio source (like an MP3 player or computer) to listen to the transmission.
You can watch the video below for step-by-step instructions and visit the project page for details and schematics.